A new method of testing CNS-active compounds (Hole Test)

Summary

A new method suitable for testing psychotropic drugs in the rats is described. The method is based on laboratory observation of the behaviour of rat before a hole; on being placed in its vicinity the animals enter into it very quickly. The hole is round, of the size of a rat's body, located on the roof of a wooden, slightly darkened cage. By varying the mutual relations of the components (cage, the size of the hole, location, lighting) we could establish that only a hole of given dimensions could serve as a basis for the test and that the other components had only minor significance.

A series of psychotropic drugs differing considerably from each other were tested. In addition to depressant compounds antidepressant and psychostimulatory substances were found to produce a marked effect. At variance with the psychostimulants the antidepressants produce their effect only in animals whose reaction time was delayed because of a prolonged treatment. A definitely positive effect, shortening the reaction time, was registered in the acute experiment. The method has proved to be highly economical. Only few animals have to be rejected, and the required personnel is limited to a small number.